In recent years, touchscreen panels have come to be broadly used in smartphones, tablet type mobile terminal devices, and the like. Various approaches are known for touchscreen panels, e.g., the resistive type, the capacitive type, and the optical type. Among others, projected capacitive touchscreen panels are becoming prevalent because of their multi-touch capabilities and highly precise detection of touched positions. Hereinafter, touchscreen panels which are combined with TFT type liquid crystal display panels (hereinafter referred to as TFT-LCDs) as their display panels will be described. It will be appreciated that display panels are not limited to TFT-LCDs, but various display panels can be used, e.g., organic EL display panels and electrophoretic display panels.
Touchscreen panels come in add-on types (i.e., those including a touch panel that is disposed on the viewer side of a polarizer (called a front polarizer) which is already disposed on the viewer side) as well as ON-cell types and IN-cell types. Herein, ON-cell types and IN-cell types will be collectively referred to as integrated types. As used herein, a cell means a display cell. For example, a liquid crystal display cell would include a pair of substrates (e.g., a TFT substrate and a counter substrate) opposing each other via a liquid crystal layer, and is not inclusive of the polarizer(s). ON-cell types refer to those in which a layer that is responsible for touchscreen function is interposed between a polarizer and a counter substrate of the liquid crystal display cell, whereas IN-cell types refer to those in which a layer that is responsible for touchscreen function is provided on the liquid crystal layer side of the counter substrate of the liquid crystal display cell, or on the TFT substrate. As compared to an add-on type touchscreen panel, an integrated type touchscreen panel is advantageous with its thinner profile of the entire device (including the TFT-LCD as well as the touch panel), light weight, and narrow frame, while also having the advantage of enhanced transmittance.
Patent Document 1 discloses a capacitive touchscreen panel of the IN-cell type. The touchscreen panel described in Patent Document 1 includes a single electrically conductive layer that has been patterned, in which a plurality of sensing electrodes (also referred to as “receiving electrodes”) and a plurality of driving electrodes (also referred to as “transmitting electrodes”) are formed. Either the sensing electrodes or the driving electrodes extend along the Y direction, while the others extend along the X direction, such that electrostatic capacitance portions that are created in the portions where they come close define sensor portions (which are the “capacitive sensing units 5” in Patent Document 1).
Patent Document 1 provides an advantage of ease of manufacture, because of having a simple structure over any touchscreen panel which includes two electrically conductive layers (an electrically conductive layer including the sensing electrodes and an electrically conductive layer including the driving electrodes) that are located above and below a dielectric layer.